It is known that conventional soft gelatin capsules are a preferred from of administration for medicaments and similar products; especially liquids, pastes, solids dispersed in liquids, or dry solids. Soft gelatin capsules also possess particular advantages for substances which require total protection from air and light, because the gelatin is completely sealed around the contents. An important example is for the encapsulation of vitamins, which has resulted in a high degree of stability thereof.
Hard gelatin capsules are also known in the art, and are generally formed from two distinct parts, namely the "cap" and the "body", fitting one into the other so as to form the complete capsule. The cap and the body are manufactured by the same process consisting of immersing in a gelatin solution the end of a mandrel whose form corresponds to the inner volume of the cap or of the body, then withdrawing the mandrel from the solution and letting the layer of gelatin thus deposited dry, which is then removed like a glove finger. Hard shell capsules so formed have problems of leakage and do not provide adequate protection from air and light. Attempts to seal hard shell capsules have generally proven uneconomical because of the need for additional equipment and materials. See e.g., Pace, U.S. Pat. No. 4,325,761; Goutard et al., U.S. Pat. No. 4,403,461; and Graham, U.S. Pat. No. 4,820,364.
Also to be mentioned are foam soft gelatin capsules, which are formed by a homogeneous microdispersion of a gas in a mixture of dry gelatin and one or more plasticizers. Mayer et al. in U.S. Pat. No. 4,719,112 disclose forming foam capsules by dip molding. Wittwer et al. U.S. Pat. No. 4,609,403 disclose employing a reciprocating die or rotary die apparatus to form the foam soft gelatin capsules.
In general, methods for producing soft shell gelatin capsules have been performed on rotary-type apparati. Chasman et al., U.S. Pat. No. 4,655,027 disclose an apparatus for forming a sealed capsule containing a powdered pharmaceutical material therein which employs a cylindrical punch roll having a radially extending chamber and a cylindrical transfer roll for forming and filling the capsules. Ishikawa et al., U.S. Pat. No. 4,817,367 also describe an apparatus and method for manufacturing gelatin capsules. The patentees teach an apparatus comprising a gelatin sheet forming mechanism which includes a rotatable cooling drum, a gelatin capsule forming mechanism which includes a pair of die rolls, and a gelatin capsule recovery mechanism. Stirn et al. in commonly assigned U.S. Pat. No. 2,775,267 describe an apparatus comprising a casting wheel for forming the gelatin strips and a cavity die roll for forming and filling the gelatin capsules.
These devices all describe a filling mechanism located on a rotary, cylindrical or roll type apparatus. Use of such a filling mechanism has resulted in the spillage or leakage of the powder, liquid or granule substance sought to be filled into the capsule, It has now been discovered that the use of a linked track of cavity blocks to form a ribbon of gelatin into a half capsule allows the filling and sealing of the powder, liquid of granule to be carried out on a substantially horizontal plane, thereby significantly reducing product spillage and defective capsules.